Method of manufacturing internal combustion engine cylinder heads



June 10, 1969 G. DE COYE DE CASTELET 5 METHOD OF MANUFACTURING INTERNAL COMBUSTION ENGINE CYLINDER HEADS Filed Nov. 30, 1964 Fig- 7 9 atan dado; c e [ask/a? 5 1%, M 72% %zw 172 Man Z0! United States Patent Im. c1. Bis /00 U.S. Cl. 29156.4 8 Claims ABSTRACT OF THE DISCLOSURE A method of manufacturing a pressure or chill cast aluminum alloy cylinder head for internal combustion engines, including the steps of machining out bores in a main casting between the valves of the engine and their corresponding manifolds, after which an aluminum alloy tube is inserted and secured in a fluid tight manner into each of said bores.

This invention relates to internal combustion engine cylinder heads and concerns a method of manufacturing such cylinder heads that is designed to facilitate their production in the form of pressureor chill-cast aluminium alloy parts for use with light metal engines.

Provided they are properly made such aluminum alloy cylinder heads afford the following advantages:

(i) an improved likelihood of obtaining sound parts;

(ii) the greater probability of obtaining water and gas passages of correction section, free from distortion or flash;

(iii) reduced cost price, because of fewer rejects obtained and because of a reduced number of parts that need to be made fluid-tight by impregnation.

Since the water chamber of a cylinder head is a closed chamber, it is clear that the cylinder head will invariably have to be made in two parts, one of which customarily forms a cover for sealing off this chamber. In specific cases where the water chamber has a lateral opening, this sealing function can be performed by the inlet or exhaust manifold.

Heretofore, however, the difficulty still remained that in order to ensure water circulation around the inlet and exhaust ducts, it was necessary to use ceramic cores between the cylinder head face (i.e. the cylinder head face mating with the cylinder) and the duct which was a costly solution hardly compatible with the mechanisation of pressure or chill-casting methods. Alternatively it was necessary to provide an opening in the cylinder head face, which in turn means that the cylinder head gasket is in contact with the cooling water over a large area, and such contact is usually detrimental to durability of the gasket.

The subject improvements of the present invention consist essentially in providing a water chamber that can be stripped from the casting mould in the normal way while at the same time enabling great cylinder-head joint face rigidity to be preserved. This is achieved by using inserted inlet and exhaust ducts which are fitted into the cylinder head after suitable machining.

The invention will now be more particularly described with reference to the accompanying exemplary drawing which shows a cylinder head with parallel valves devised according to the invention and obtained by performing the subject method of the invention, though it is to be clearly understood that the present invention is applicable to any type of cylinder head.

Patented June 10, 1969 p I C6 In the drawing:

FIGURE 1 shows a cylinder head in interrupted crosssection taken through a valve axis and through a spark plug axis; and

FIGURE 2, 3 and 4 show alternative methods of fitting the inlet and exhaust ducts to the main cylinder casting.

Referring first to FIGURE 1, the cylinder head shown thereon consists of a main casting 1 and a cover 2.

These two sections are assembled together as at 3, preferably by means of a bonded joint, though it is to be understood that a conventional gasket may be used if desired.

The degree of accuracy obtained with pressure casting does not exclude the possibility of assembling the two sections together without prior machining of the mating surfaces.

The central portions 4 of the inlet and exhaust tracts of the cylinder head casting 1, designed to accommodate the valves, are cast in by means of a corepiece 4' (a cylindrical insert which can usually be stripped by a sliding motion). This corepiece is slidable in an inclined direction within the mould used for said cylinder head casting.

The bores 5 of the inlet and exhaust tracts themselves can likewise be rough-cast by means of a horizontally movable second corepiece 6.

After the casting 1 and the cover 2 have been joined together as stated precedingly, the assembly is then machined; this consists in machining the cylinder-head and cylinder mating faces, in calibrating the bores 5, in machining the bores 7 and in rounding off the corner remaining at 8.

After these operations have been completed, the next step is to fit the inlet and exhaust ducts 9 which have port in the central portion 4. These ducts preferably consist of aluminium alloy tubes varying in thickness between two and four millimetres.

These tubes may be fitted to the cylinder head casting in the manner shown in FIGURE 1, namely by driving them with a gripping fit into the bores '5 and 7 and subsequently bonding them thereto, if desired, with a hydrocarbon-resisting substance.

Alternatively, the tubes may be fitted in the manner shown in FIGURES 2, 3 and 4. In the specific example of FIGURE 2, the tubes 9 are easy fits in the bores 5 and 7, fliud-tightness being obtained at both the manifold end and the valve end by means of a metal-and-asbestos gasket 10. In the example of FIGURE 3, the tube 9 is a tight fit and is possibly bonded, at the valve end, i.e. as at 11, whereas at the manifold end it is sealed by means of a special solder 12.

Referring lastly to FIGURE 4 for a third alternative embodiment, the tract shown thereon utilizes a metal-andasbestos gasket 10 at the valve end and a threaded and possibly bonded form of assembly 13 at the manifold end. It is, however, to be understood that any other means may be resorted to for effecting such amembly without departing from the spirit and scope of the present invention.

Reference numeral 14 designates the spark plug hole in the cylinder head.

What is claimed is:

1. A method of manufacturing an internal combustion engine comprising the steps of pressure casting an aluminum alloy cylinder head, forming inlet and exhaust manifolds and valves, casting a main casting, casting a cover part for said main casting, assembling said cover part over said main casting, machining out bores in said main casting between said valves and their corresponding manifolds, inserting an aluminum alloy tube into each of said bores, and securing said tubes in said bores in a fluid tight manner to form inlet and exhaust ducts.

2. A method according to claim 1, wherein said tubes are force fitted in said machined bores.

3. A method according to claim 1, wherein said are bonded in said bores.

4. A method according to claim 2, wherein said tubes are bonded in said bores.

5. A method according to claim 1, wherein said tubes are loosely fitted in said bores, fluid tightness 'being obtained by means of metal and asbestos gaskets both at the manifold end and the valve end.

6. A method according to claim 1, wherein said tubes are tightly fitted in said bores and are bonded thereto at the valve end and welded thereto at the manifold end.

7. A method according to claim 1, wherein said tubes are assembled with a metal and asbestos gasket at the valve end and secured by means of screw threaded engagement at the manifold end.

8. A method according to claim 7, wherein said tubes are also bonded at the manifold end.

tubes Larson 29-1564 X [Herreshofi et a1. 29-156.4 X Girard 29-1564 S-choessow.

Mills 29-455 Highsmith.

Rohe et a1. 29-455 Hepner.

JOHN F. CAMPBELL, Primary Examiner.

P. M. COHEN, Assistant Examiner.

US. Cl. X.R. 

